The UK patent application GB2379299A discloses a 3D graphics system processing encrypted texture data. The graphics system has an input to receive object data for an object to be textured. The textures used by an application, especially games applications, have been created at the time the application is written. To prevent widespread duplication of the graphics software including these textures the texture data has been encrypted before distribution. The systems running the games application obtain the encrypted textures from a local memory and have a texture decryption unit to decrypt the textures on the fly for use by a render unit. The decrypted texture data generates texture image data for a frame buffer from where it can be output for display. The texture decryption unit decrypts the texture pixels by using a key based on a sales key externally supplied to the render unit. A memory encryption and decryption unit may be positioned between the memory controller and the frame memory.
A disadvantage of this prior art is that a security breach occurs as soon as the sales key and, if present, the key for encrypting the data in the frame memory becomes known.